Pen



FIG. 1 is a front right perspective view of a pen showing my new design;

FIG. 2 is a left elevational view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a right elevational view thereof; and,

FIG. 5 is a rear elevational view thereof.

The stippling shown in the drawings represents a texture on the surface of the pen. 

The ornamental design of a pen, as shown and described. 